GRANT=P50MH58911-06-0005 The focus of Project 1 is on the normal mechanisms of fear, and the effects of stress on these in both rats and humans. All studies involve interactions with other members of the Center, as described below. Six rat studies are proposed. Study 1 examines the effects of stress on conditioned fear, including an analysis of individual and sex differences. The role of glucocorticoids in mediating effects of stress on fear will be determined. Study 2 assesses whether the effects of stress on fear are due to actions of stress hormones in the amygdala or other regions of the conditioned fear circuitry (medial prefrontal cortex, hippocampus, bed nucleus of the stria terminalis). Study 3 evaluates the effects of stress and stress hormones on the physiology of the amygdala cells and their plasticity. Study 4 examines the extent to which stress and/or fear conditioning produce structural changes in dendritic morphology or spine organization in the amygdala, and examines the molecular mechanisms mediating structural changes. Study 5 continues on-going projects on the mechanisms by which mediations like SSRIs regulate conditioned fear. Study 6 explores reconsolidation of fear in an effort to identify, though animal studies, pharmacological agents that are safe and practical to use during memory retrieval in an effort to block the later survival and/or access to traumatic memories. The human studies are led by Elizabeth Phelps of NYU. Results of these will feed into the design of new patient studies for Project 2. Study 1 builds upon the ideas from the rat studies above and examines whether individual or sex differences in trait anxiety, HPA response, or in the response to acute brain activation patterns different between high and low anxious individuals during fear conditioning and active coping. Study 3 examines active coping in patients with anxiety disorders. Studies 4 and 5 explore the possibility that pharmacological manipulation of memory during retrieval might alter the survival or accessibility of memory and thus might be useful in treating traumatic memory symptoms in PTSD.